Method of rectifying alternating currents



March 4, 1930 F. SCHROTER METHOD OF RECTIFYING ALTERNATING CURRENTSFiled March 16' 1921 anvemtoz Mme/1 Patented Mar. 4, 1930 UNITED STATESPATENT OFFICE FRITZ SGHROTER, OF BERLIN, GERMANY, ASSIGNOR TO SAFETY CARHEATING & LIGHTING COMPANY, A CORPORATION OF NEW JERSEY METHOD OFRECTIFYING ALTERNATING CURRENTS Application filed. March 16, 1921,Serial No.

This invention relates in general to alternating current rectifiersemploying a gaseous conduction .device and relates more particularly toan improved method of rectifying alternating currents by means ofgaseous discharge.

One of the objects of this invention is to provide a method ofconstructing a gaseous discharge alternating current rectifier ofeffective and reliable action and to provide a method of constructionand operation of rectifiers of the above type by which certaindisadvantages resulting from the absorption of the gaseous content bythe material of the electrodes are avoided and by which the life of therectifying discharge tube is greatly prolonged. Other objects will be inpart'ohvious or in part pointed out hereinafter.

The invention accordinglyconsists in the features of construction.combinations of elements and sequence of steps as would be exemplifiedin the following description and the scope of the application of whichwill be indicated in the following claims.

In the accompanying drawing in which are shown several of variouspossible embodiments of the mechanical features of this invention,

Figure 1 is a central cross section of a gaseous conduction deviceadapted to operate as a rectifier; and

Figure 2 is a similar central cross-sectional view of a modified form ofgaseous conduction device, the latter being shown in this figure asrelated to an electric circuit for rec- .tifying action.

Rectifying tubes employing dissimilarly proportioned electrodes and agaseous content composed, for example, of gases of the helium group, arefound to be substantially uni-directional in their action upon analternating current and are found to permit the passage therethrough ofonly those alternations which are of one polarity. Tubes of thischaracter, however, are found to permit also the passage in a greatlydecreased magnitude of those alternations of the alternating currentwhich are of the opposite polarity and which it is desired to suppress.Such alternations of currentof opposite polarity which 452,825, and inGermany November 3, 1919.

the discharge tube is to choke off or substantially prevent the passageof, are found to exhibit a high cathode drop in potential andaccordingly to cause an intense volatilization of the metal of therectifying anode. Such a volatilization takes place in the form of smallparticles of the electrode material emanating from the anode insubstantially all directions therefrom and into the gaseous atmosphereof the tube. The small particles of the electrode material thus emanatedfrom the surface thereof cause an undesired absorption of the gaseouscontent and thus, in so affecting the gaseous content, cause a materialdiminution in the life and effectiveness of the rectifying tube.

It is one of the aims of this invention to avoid the detrimental effectsof such absorption and in accordance with the method of this invention,the cathode is so positioned with respect to the anode that the formersubstantially surrounds the latter and is in substantially closeproximity thereto. In the normal operation of a glow-discharge tube ofthis type, the temperature of the cathode 7 is relatively high ascompared with temperatures existing in other parts of the tube. Byreason of the relative location of the cathode with respect to theanode, the metal particles which emanate in substantially all directionsin addition to normal from the individual surface elements of the anodeare made to strike or impinge as completely as possible upon the heatedsurface or to enter the regions in immediate proximity to the cathode,whose temperature is considerably higher than that of the anode or ofthe particles emanating therefrom. Hence, the particles resulting fromthe volatilization of the anode and which absorb the gases of theatmosphere are heated by their contact with the cathode surface or bytheir entry into the cathode regions to the higher temperature thereofand are thus made to return or emit the gases absorbed by them. Thegaseous content of the tube during its functioning is thus maintainedsubstantially intact and no losses result therein by reason of theabsorption as hereinbefore pointed out. The discharge tube is thus madecapable of functioning efiiciently and substan- 1C0 tially the samenumber of molecules of the ing more specifically the manner in which theelectrodes are mounted within the vessel 10, it will be seen that withinthe vessel 10 and suitably sealed to the bottom portion thereof there isa post or pedestal 13 adapted to support at its lower end, as by meansof the wires 14, the one end of the electrode 11 which preferably ismade of sheet metal and bent or formed into a cylindrical shape. Thewires 14 are fused into the glass pedestal 13 \.25 and one of them isextended as at 15 .to the exterior of the vessel 10to form one of theconducting elements of the gaseous conduction device. At the upper endof the cylindrically shaped electrode 11 there are provided wires 16which, like the supporting wires 14 hereinabove mentioned, arepreferably welded or otherwise suitably secured to the electrode 11. Thewires 16 are extended upwardl and at their ends are provided withsuitablh insulating beads17 which may take the form of glass and whichmay be fused into the interior wall-forming parts of the vessel 10thereby to rigidly hold the electrode 11 in position.

Extending through the glass pedestal 13 is a conductor 18 which iselectrically connected at its upper end to the electrode 12 hereinbeforementioned. The electrode 12 preferably takes the form of a heavy wiresuitably sup orted upon or fused into the upper end 0 the post 13. Theelectrode 12 is surrounded by an insulating tube 19 spaced therefrom andthis tube 19 is in turn surrounded by an insulating tube 20 also inspaced relation with the tube 19. This construction is adapted toprevent the formation of a continuous coating adjacent the electrode 12by reason of the deposition upon the parts surrounding the electrode 12of metal lic particles emanating from the electrodes durmg their 0ei'ation. This construction, it may be note forms no part of thisinvention and as for the details thereof reference may be had to theco-pending application of Otto Schaller and Frltz Schrfiter, filed July22, 1920, Serial No. 398,276.

In the operation of the device the electrode 12 is adapted to functionas the anode and the electrode 11 is adapted to function as 65 thecathode. When connected into the circuit of an alternating currentsource of supply the gaseous content will become ionized and the currentwill flow from the anode 12 to the cathode 11, by reason of thedissimilarity of the electrodes, it being noted that the cathode 11 isof extremely large surface area relative to that of the anode 12. Thecurrent thus flowing in this direction is made possible by'reason of thelarge surface of the cathode 11- which may be considered as permittingthe flow thereto and reception thereon of a much greater number ofelectrons emanating from the anode 12 than could take place in thereverse direction.

When, however, that alternation of the alternating current which it isdesired to suppress becomes efl'ective upon the electrodes of thedevice, the effect thereof will be to make the electrode 12 act as theoathode and the electrode 11 as the anode.

Butbecause-of its relatively small active.

surface when acting normally as above described, the electrode 12 is ata relatively high temperature because of the high 'intensity of thecurrent -flow therefrom to the cathode 11. The electrode 12 therefore,is, during the period in which it acts as a catho e, strongly inclinedtowards disintegration and metallic particles thereof are projected oremanated therefrom.

As has been hereinbefore noted, the particles resulting from thevolatilization of the electrode abssorb the gases of the atmospherecontained within the vessel 10 and thus brin about detrimental eifectsupon. the life and effectiveness of the rectifying tube. But it will beseen that the cathode 11 which during normal operation attains arelatively high temperature, substantiall entirely surrounds the anode12 and t us intercepts the particles emanating from the anode'12. The

emanating particles which occlude the gases .in the vessel 10 are thusheated as soon-as they contact with the surface of the cathode 11 or assoon as they enter into the cathode region of a higher temperature. Suchparticles are thus raised. 1n temperature and 7 hence are made to returnor absorbed by them.

In Fig. 2 is illustrated a modified embodiemit the gases ment of-themechanical features of this in vention and it will be noted that thevessel 10 is provided with a post or pedestal 13 in the upper end ofwhich is mounted the anode 12' in a manner substantially similar to thatin which the anode 12 of Fig. 1 is mounted. The protective insulatingtubes 19 and 20' provide intervening spaces for preventing the formationof a continuous coating by the deposition of particles emanating fromthe electrodes. Upon the base portion 13 of the post 13' is mounted theother electrode 11 adapted to function as the cathode, and it will beseen that it is supported thereon by means of the supporting wires 14one of which is extended as at 15 to the interior of the vessel 10" toform an electrical connection to the exterior. The electrode 11, it willbe seen, is of a general cylindrical shape and is composed of a suitablesheet metal; and it will be seen that at its upper end it is closed bythe dome-like cap 11'. Also it will be noted that at the upper end it issupported by means of the supporting wires 16 and the insulating beads17" adapted-to contact with the interior wall of the vessel 10" andadapted also to be fused thereto. Throughout the electrode 11 there aresubstantially uniformly distributed a plurality of openings 21.

The anode 12 is connected by means of the conducting element or wire 18to the exterior of the vessel 10 and it will be seen that thisconducting element 18* may conveniently extend to the supporting post13. In Fig. 2' there is also diagrammatically illustrated an electriccircuit in which the use of the rectifying gaseous conduction devices ofeither Fig. 1 or Fig. 2 is illustrated. It will be seen that the circuitcomprises a source 22 of alternating current and, for the sake ofillustration, it is assumed that itis desired to rectify the currenttherefrom into direct or unidirectional current for the purpose ofcharging a storage battery indicated at 23. In the same circuit isincluded a variable resistance 24 adapted to regulate the intensity ofcurrent flowing to the storage battery. The rectifying tube'is alsoconnected in the circuit and it will be noted that the anode 12 and thecathode 11' are so connected therein that the current in the entirecircuit can flow only in the direction of the arrow indicated at 25,this direction of flow being determined by the current flow from theanode 12 to the cathode 11.

In the operation of the rectifying device illustrated in Fig. 2, theopenin s 21" permit the exterior surface of the catho e 11" to take partin the rectifying action; that is, the

openings 21 provide a path for the current flowing from the anode 12through the openilrigs 21 to the exterior surface of the cathode Theanode 12 has a great tendency to disintegrate and to give off metallicparticles therefrom, much in the same manner as described in connectionwith the anode 12 of the device illustrated in Fig. 1. But the cathode11 substantially entirely encloses or surrounds the anode 12*, since thedomeshaped cap 11 forms with the side cylindrical walls of the cathode11 a substantial enclosure for the anode 12. Thus the articles emanatingfrom the anode 12" w ich, as

hereinbefore noted, tend to occlude the gasesin the vessel 10" are madeto impinge upon the surface of the cathode 11' or are made to enter theregion adjacent the cathode 11, whereby said particles are raised intempertrated in Figs. ,1 and 2, thus making themhighly dissimilar withrespect to the oath odes. The anodes may also, for example, be made ofiron wire.

It will thus be seen that there has been provided in this invention anapparatus and method by means of which the detrimental occlusion orabsorption of the gaseous content of the gaseous discharge evice iseffectively prevented, and that the method and apparatus thus providedby this invention insures the presence in the discharge or rectifyingdevice of substantially the same number of molecules of the gaseouscontent at all times available for ionization. The proper and desiredaction of the tube is thus maintained and the life thereof materiallyenhanced.

Since various changes might be made in the invention and in the stepsthereof hereinbefore set forth, it is to be understood that all matterhereinbefore set forth is to be interpreted as illustrative and not in alimitmg sense.

I claim as my invention:

1. In rectifying tubes of the gaseous conduction type having a metallicanode and a cathode, the method of preventing the per-- manentabsorption of the gaseous content cles emanated from the anode toimpinge upon the surface of the cathode whereby such particles areraised in temperature and are caused to emit gases absorbed thereby. -2.In rectiqin tubes of the gaseous conduction type avmg a metallic anodeand a cathode, the method of reventing the permanent absorption of egaseous content which consists in raising the temperature of themetallic particles emanated from the surface of the anode to cause saidparticles to emit the gases absorbed thereby, by utilizing the heatproduced at the cathode.

In testimony whereof, I have si name to this specification this 22nJanuary, 1921.

ed my day of DR. FRITZ soHRoTER.

